1. Field of the Invention
This invention relates to an oil field tool for use in an oil and gas well where the casing is cracked or otherwise leaking to seal off the well below the crack or leak and divert the gas to the inside of the tubing for travel to the surface. More specifically, the present invention relates to a tubular body serially connected in a well tubing string below a packer and includes valved passageways for the passage of the well gas from the exterior of the tubing string to the interior of the body for carrying the gas up the tubing string to the surface.
2. Description of Related Art
Oil and gas wells with cracked casings present problems to economical removal of the oil and gas. Typically, the crack or hole in the casing permits contaminating materials, such as water and mud, to enter the well and flood out the productive oil and gas zone, thereby rendering a marginal well uneconomical to pump the oil to the surface. The conventional solution is to repair the casing at the crack or hole by the "cement squeeze" process; however this is very costly and is not economically feasible in marginal wells. Further, there is no assurance a "cement squeeze" repair will hold. Thus, there is a great demand for a simple and inexpensive tool which can be utilized in wells having a cracked or leaking casing, especially marginal wells, to make the wells productive. The U.S. patent art includes various prior patents which disclose excess gas pressure diversion and venting structures as well as sealing and fluid bypass structures that pertain to improvements in well production. For example, Mack U.S. Pat. No. 1,536,348 discloses a gas venting tool disposed in a tubing string below a packer and capable of enabling the flow of gas from the exterior of the tubing string into the interior of the latter. However, the Mack gas venting tool is made as part of the packer and is designed to be used in conjunction with and sealed relative to the upper end of a "bottom casing".
Lynn U.S. Pat. No. 1,238,165 also discloses a gas venting tool, but the Lynn tool is interposed between two laterally offset tubing sections and therefore prevents the passage of various repair and/or service tools downwardly through the tubing string past the venting tool. Also, it would appear that the Lynn tool would not provide sufficient clearance for a pump rod. Carlton et al. U.S. Pat. No. 5,507,343 discloses an apparatus for repairing a damaged well casing and employs two packers with gas vents.
Ames U.S. Pat. No. 1,139,745 is directed toward an apparatus for evacuating gas from a closed well to permit the continuing flow of oil into the well casing. Roeder U.S. Pat. No. 3,625,288 discloses a pump assembly providing a plurality of passageways to accommodate oil, gas and power fluid flow as well a structure for alternately using the various passageways. Jacobi U.S. Pat. No. 5,390,737 discloses a packer assembly with a sliding valve to be opened or closed manually, and Renfroe U.S. Pat. No. 4,834,176 discloses a device for opening a valve to communicate the exterior and interior of the tool. The patents to Pistole et al., U.S. Pat. No. 2,804,147 and to Koster, U.S. Pat. No. 5,046,558 disclose structures for sealing leaks in casings. Finally, Falk U.S. Pat. No. 2,913,054 discloses a device for closing a connection in the tubing string between different zones separated by a packer, and Hesh U.S. Pat. No. 4,844,156 discloses a method for promoting increased formation flow.
However, the prior art does not disclose a simple and inexpensive tool that can be readily inserted into a tubing string below a casing sealing (tension) packer and that will divert gas buildup outside of the tubing below the packer and allow the gas to flow to the surface along with the oil being pumped up the tubing.